package com.infomancers.collections.tree;

/**
 * Copyright (c) 2007, Aviad Ben Dov
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this list
 * of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice, this
 * list of conditions and the following disclaimer in the documentation and/or other
 * materials provided with the distribution.
 * 3. Neither the name of Infomancers, Ltd. nor the names of its contributors may be
 * used to endorse or promote products derived from this software without specific
 * prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */


/**
 * Used as an adapter between an already existing tree
 * model and this collections library.
 * <p/>
 * A few well known trees already have implementations in this
 * library, such as TreeModelAdapter for Swing's TreeModel interface
 * and DOMAdapter for XML DOM.
 *
 * @see com.infomancers.collections.tree.DOMAdapter
 * @see com.infomancers.collections.tree.TreeModelAdapter
 */
public interface TreeAdapter {
    /**
     * Retrieves the root of the tree.
     * <p/>
     * Cannot return null.
     *
     * @return The root of the tree.
     */
    Object getRoot();


    /**
     * Retrieves the children of the node specified. If the node
     * has no children (is a leaf), an empty iterable is returned.
     * <p/>
     * Cannot return null.
     *
     * @param node The node to retrieve the children for.
     * @return The children nodes of the node.
     */
    Iterable<Object> getChildren(Object node);
}
